running for long enough...

[Andre W B Furtado]

Actually, my version of the program would halt and print the "SWITCHED!"
message if it changed from "a"s to "b"s. But that's ok, I understood why
this example won't work well in GHC, but isn't it too disappointing that the
"Haskell Concurrent basic example for beginners" is not working well?

Andre.


----- Original Message -----
From: Simon Marlow <simonmar@microsoft.com>
To: Andre W B Furtado <aw@free.elogica.com.br>; <haskell@haskell.org>
Cc: <alms@cin.ufpe.br>; <jeaf@cin.ufpe.br>
Sent: Wednesday, April 25, 2001 7:57 AM
Subject: RE: running for long enough...


> > About the program below, someone (I think Simon Marlow) said
> > that if I run
> > it for long enough, I'll see "a"s rather than "b"s. I would
> > like to know for
> > how long I will have to wait, since 2 hours were not enough to see it
> > switching from "b"s to "a"s.
> >
> > > main = forkIO a >> b
> > >  where
> > >   a = putStrLn "a" >> a
> > >   b = putStrLn "b" >> b
>
> Did you watch it continuously for two hours?  It might have changed
> quicky to "a"s and back again without you noticing.  Watch it very
> carefully.
> <mischevous grin> :)
>
> But seriously, don't waste your time on this example.  It just doesn't
> work too well with GHC, because of the contention between the two
> threads both trying to access standard output.
>
> Cheers,
> Simon
>